1. With the exception of substance abuse and anxiety disorders, any past or current Axis I diagnosis other than Major Depressive Disorder. With regard to substance abuse disorders, we will allow past diagnoses so long as there is no question of substance or alcohol dependence, the patient has not had substance abuse patterns in the year prior to enrollment, and other criteria regarding LSD and ecstasy use are met (see below). We will screen for substance abuse patterns in the year prior to enrollment by excluding heavy alcohol use, as defined as greater than 14 drinks per week for men and greater than 7 drinks per week for women. With regard to anxiety disorders, we will allow past or present diagnoses of Generalized Anxiety Disorder, social phobia and panic disorder, so long as the anxiety disorder is not felt to outweigh the magnitude of the diagnosis of Major Depressive Disorder. This will be determined by clinical investigators in this protocol. Particular attention will be made to ensure that the patient does not have a diagnosis of Bipolar disorder, Schizoaffective disorder or Premenstrual dysphoric disorder (PMDD).